171 lines
4.3 KiB
ReStructuredText
171 lines
4.3 KiB
ReStructuredText
.. SPDX-License-Identifier: GPL-2.0
|
|
|
|
========================
|
|
Spear PCIe Gadget Driver
|
|
========================
|
|
|
|
Author
|
|
======
|
|
Pratyush Anand (pratyush.anand@gmail.com)
|
|
|
|
Location
|
|
========
|
|
driver/misc/spear13xx_pcie_gadget.c
|
|
|
|
Supported Chip:
|
|
===============
|
|
SPEAr1300
|
|
SPEAr1310
|
|
|
|
Menuconfig option:
|
|
==================
|
|
Device Drivers
|
|
Misc devices
|
|
PCIe gadget support for SPEAr13XX platform
|
|
|
|
purpose
|
|
=======
|
|
This driver has several nodes which can be read/written by configfs interface.
|
|
Its main purpose is to configure selected dual mode PCIe controller as device
|
|
and then program its various registers to configure it as a particular device
|
|
type. This driver can be used to show spear's PCIe device capability.
|
|
|
|
Description of different nodes:
|
|
===============================
|
|
|
|
read behavior of nodes:
|
|
-----------------------
|
|
|
|
=============== ==============================================================
|
|
link gives ltssm status.
|
|
int_type type of supported interrupt
|
|
no_of_msi zero if MSI is not enabled by host. A positive value is the
|
|
number of MSI vector granted.
|
|
vendor_id returns programmed vendor id (hex)
|
|
device_id returns programmed device id(hex)
|
|
bar0_size: returns size of bar0 in hex.
|
|
bar0_address returns address of bar0 mapped area in hex.
|
|
bar0_rw_offset returns offset of bar0 for which bar0_data will return value.
|
|
bar0_data returns data at bar0_rw_offset.
|
|
=============== ==============================================================
|
|
|
|
write behavior of nodes:
|
|
------------------------
|
|
|
|
=============== ================================================================
|
|
link write UP to enable ltsmm DOWN to disable
|
|
int_type write interrupt type to be configured and (int_type could be
|
|
INTA, MSI or NO_INT). Select MSI only when you have programmed
|
|
no_of_msi node.
|
|
no_of_msi number of MSI vector needed.
|
|
inta write 1 to assert INTA and 0 to de-assert.
|
|
send_msi write MSI vector to be sent.
|
|
vendor_id write vendor id(hex) to be programmed.
|
|
device_id write device id(hex) to be programmed.
|
|
bar0_size write size of bar0 in hex. default bar0 size is 1000 (hex)
|
|
bytes.
|
|
bar0_address write address of bar0 mapped area in hex. (default mapping of
|
|
bar0 is SYSRAM1(E0800000). Always program bar size before bar
|
|
address. Kernel might modify bar size and address for alignment,
|
|
so read back bar size and address after writing to cross check.
|
|
bar0_rw_offset write offset of bar0 for which bar0_data will write value.
|
|
bar0_data write data to be written at bar0_rw_offset.
|
|
=============== ================================================================
|
|
|
|
Node programming example
|
|
========================
|
|
|
|
Program all PCIe registers in such a way that when this device is connected
|
|
to the PCIe host, then host sees this device as 1MB RAM.
|
|
|
|
::
|
|
|
|
#mount -t configfs none /Config
|
|
|
|
For nth PCIe Device Controller::
|
|
|
|
# cd /config/pcie_gadget.n/
|
|
|
|
Now you have all the nodes in this directory.
|
|
program vendor id as 0x104a::
|
|
|
|
# echo 104A >> vendor_id
|
|
|
|
program device id as 0xCD80::
|
|
|
|
# echo CD80 >> device_id
|
|
|
|
program BAR0 size as 1MB::
|
|
|
|
# echo 100000 >> bar0_size
|
|
|
|
check for programmed bar0 size::
|
|
|
|
# cat bar0_size
|
|
|
|
Program BAR0 Address as DDR (0x2100000). This is the physical address of
|
|
memory, which is to be made visible to PCIe host. Similarly any other peripheral
|
|
can also be made visible to PCIe host. E.g., if you program base address of UART
|
|
as BAR0 address then when this device will be connected to a host, it will be
|
|
visible as UART.
|
|
|
|
::
|
|
|
|
# echo 2100000 >> bar0_address
|
|
|
|
program interrupt type : INTA::
|
|
|
|
# echo INTA >> int_type
|
|
|
|
go for link up now::
|
|
|
|
# echo UP >> link
|
|
|
|
It will have to be insured that, once link up is done on gadget, then only host
|
|
is initialized and start to search PCIe devices on its port.
|
|
|
|
::
|
|
|
|
/*wait till link is up*/
|
|
# cat link
|
|
|
|
Wait till it returns UP.
|
|
|
|
To assert INTA::
|
|
|
|
# echo 1 >> inta
|
|
|
|
To de-assert INTA::
|
|
|
|
# echo 0 >> inta
|
|
|
|
if MSI is to be used as interrupt, program no of msi vector needed (say4)::
|
|
|
|
# echo 4 >> no_of_msi
|
|
|
|
select MSI as interrupt type::
|
|
|
|
# echo MSI >> int_type
|
|
|
|
go for link up now::
|
|
|
|
# echo UP >> link
|
|
|
|
wait till link is up::
|
|
|
|
# cat link
|
|
|
|
An application can repetitively read this node till link is found UP. It can
|
|
sleep between two read.
|
|
|
|
wait till msi is enabled::
|
|
|
|
# cat no_of_msi
|
|
|
|
Should return 4 (number of requested MSI vector)
|
|
|
|
to send msi vector 2::
|
|
|
|
# echo 2 >> send_msi
|
|
# cd -
|